In typical computer systems, processors are implemented to operate on values represented by a large number of bits (e.g., 64) using instructions that produce one result. For example, the execution of an add instruction will add together a first 64-bit value and a second 64-bit value and store the result as a third 64-bit value. Multimedia applications (e.g., applications targeted at computer supported cooperation (CSC—the integration of teleconferencing with mixed media data manipulation), 2D/3D graphics, image processing, video compression/decompression, recognition algorithms and audio manipulation) require the manipulation of large amounts of data. The data may be represented by a single large value (e.g., 64 bits or 128 bits), or may instead be represented in a small number of bits (e.g., 8 or 16 or 32 bits). For example, graphical data may be represented by 8 or 16 bits, sound data may be represented by 8 or 16 bits, integer data may be represented by 8, 16 or 32 bits, and floating point data may be represented by 32 or 64 bits.
To improve efficiency of multimedia applications (as well as other applications that have the same characteristics), processors may provide packed data formats. A packed data format is one in which the bits typically used to represent a single value are broken into a number of fixed sized data elements, each of which represents a separate value. For example, a 128-bit register may be broken into four 32-bit elements, each of which represents a separate 32-bit value. In this manner, these processors can more efficiently process multimedia applications.